Proliferation dynamics of WSSV in crayfish, Procambarus clarkii, and the host responses at different temperatures

Abstract

The replication profile of white spot syndrome virus (WSSV) in crayfish, Procambarus clarkii, at different water temperature was investigated in this study. The WSSV detections were negative at 15 ± 1°C, and the natural infection ratio increased at 19 ± 1°C (24.2% ± 2.25%), reached 100% at 25 ± 1°C and decreased at 30 ± 1°C (93.2% ± 3.37%). The WSSV genome copies number was much higher at 25 ± 1°C (≥5 × 106.45 ± 0.35/mg) than at 15 ± 1°C (≤5 × 101.13 ± 0.12/mg), 19 ± 1°C (≤5 × 102.74 ± 0.48/mg) and 32 ± 1°C (≤5 × 103.18 ± 0.27/mg). Meanwhile, the significant transcription signals of immediate early gene ie1 and late gene vp28 and a large number of virus particles were detected in epitheliums of stomach, gut and gill, hepatopancreas, heart and muscle cells at 25 ± 1°C by using in situ hybridization (ISH) and transmission electron microscopy. The experimental infection of P. clarkii with WSSV infection showed reduced mortality and lower virus copies number at 19 ± 1°C (23.51% ± 0.84%, ≤5 × 103.41 ± 0.11/mg) and 32 ± 1°C (38.42% ± 1.21%, ≤5 × 103.72 ± 0.13/mg) compared to 25 ± 1°C (100%, ≥5 × 104.99 ± 0.24/mg). The water temperature regulated the transcription of immune‐related genes (crustin2, prophenoloxidase (proPO) and heat shock protein70 (Hsp70)), with some differences between WSSV treatments and control treatments. These results demonstrate that water temperature has effect on WSSV proliferation, which may due to transcriptional response of immune‐related genes to temperature.

A novel Dicistro‐like virus discovered in Procambarus clarkii with “Black May” disease

“…Reports have also indicated that the optimum water temperature for WSSV to infect P. clarkii is 27–28°C (Guan et al., 2003; Withyachumnarnkul et al., 2003), which is consistent with the water temperature in that region in the months from June to August. Other reports have shown that the optimum water temperature for WSSV to infect P. clarkii is 25–30°C (Jiang et al., 2019; Moser et al., 2012), but the onset time of “Black May” is at the end of April and the beginning of May, when the water temperature in the middle and lower reaches and ponds of the Yangtze River is 15–20°C, which is significantly lower than the optimal water temperature for WSSV. In this study, PcDV positivity in P. clarkii coincided with “Black May” for two consecutive years, 2018–2019.…”

“…The progress of the disease is dramatic with a swift increase in death rates (Deng, Liu, & Tang 2019). To date, the pathogen responsible for the “Black May” disease in P. clarkii remains undefined, with existing research focusing mainly on the white spot syndrome virus (WSSV) (Huang et al, 2019; Jiang et al., 2019).…”

“…The progress of the disease is dramatic with a swift increase in death rates (Deng, Liu, & Tang 2019). To date, the pathogen responsible for the "Black May" disease in P. clarkii remains undefined, with existing research focusing mainly on the white spot syndrome virus (WSSV) (Huang et al, 2019;Jiang et al, 2019).Picornaviruses are spherical non-encapsulated positive-stranded RNA viruses (around 30 nm in diameter), coated with icosahedral capsid proteins. The number of identified members of this family has risen rapidly in the past ten years (Zell, 2018).…”

Determination of a novel parvovirus pathogen associated with massive mortality in adult tilapia

“…Polyclonal mouse antibody raised against non-structural protein (NS1) of TiPV was prepared by ABclonal (Wuhan, China) and used as the primary antibody. IFA was performed according to the protocol described by Ma et al [ 37 ] with slight modifications. Uninfected tissues samples and TiPV infected tissue samples were taken as negative controls and positive controls, respectively.…”

“…All the tissues were homogenized in lysis buffer, and virus genomic DNA was extracted using DNA viral kits (Omega, Germany) according to the manufacturer’s instructions. Real-time PCR reactions and quantitative analyses were performed primarily based on the previously described methods [ 37 ]. The primers used in this study are shown in Table 1 (TiPV-Fq/Rq).…”